Allogeneic Hematopoietic Stem Cell Transplantation after Conditioning Regimens with Fludarabine/melphalan or Fludarabine/busulfan for Patients with Hematological Malignancies: A Single-center Analysis

Objective Fludarabine plus melphalan (FM) and fludarabine plus busulfan (FB) are two major conditioning regimens for allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods We retrospectively analyzed patients who underwent allo-HSCT after a conditioning regimen consisting of FM or FB with/without total body irradiation for hematological malignancies between 2005 and 2014. Results There were 41 patients who met the criteria. The median follow-up time for the survivors was 3 years. Thirty-two patients received allo-HSCT after the FM regimen and nine patients received allo-HSCT after the FB regimen. Patients who received FB were older than those who received FM (p=0.041). There was no significant difference in the 3-year overall survival between patients who had received FB and those who had received FM (29.6% vs. 56.5%, p=0.267). The 3-year cumulative incidence of relapse was significantly higher in patients who had received FB than that in patients who had received FM (66.7% vs. 17.8%, p=0.004), and FB was an independent prognostic factor for relapse by a multivariate analysis (hazard ratio, 9.8; 95% confidential interval, 2.5-39.3; p=0.001). When we restricted the evaluation to patients with acute myeloid leukemia and myelodysplastic syndrome, the 3-year cumulative incidence of relapse was also significantly higher in patients who had received FB than that in patients who had received FM (75.0% vs. 16.1%, p=0.004). Conclusion The results suggest that FM may provide better disease control than FB.